Brush-holder.



E. L. CLARK.

BRUSH HOLDER. APPLICATION FILED APR. 19. was.

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E. L. CLARK.

BRUSH HOLDER. APPLICATION FILED APR. 1s, 1916.

1,293,638. Patentefi Feb.4,1919.

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EMERSON L. CLARK, OF LAKEWOOD, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 NATIONAL CARBON COMPANY, IN 0., A CORPORATION OF NEW YORK.

BRUSH-HOLDER.

Application filed April 19, 1916.

To all whom it may concern:

Be it known that I, EMERSON L. CLARK, a citizen of the United States, residing at Lakewood, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Brush-Holder's, of which the following is a full, clear, and exact description.

This invention relates to brush holders for dynamo electric, machines. In brush 'holders at present in use the brush is supforce resisting the effort of the commutator to drag the brush along with it, is through the center of the holder which may be an inch or more above the surface of the commutator. Since the turning force exerted on the brush by the commutatoris in the circumference of the commutator, there is always a considerable moment of rotation tending to tip the brush around, thus destroying the fit of the brush on the commutator. I

My invention overcomes the above diificulties and consists of an arrangement whereby the resultant reacting force is exerted in the same plane as the turning force due to friction on the commutator, namely in a plane tangent to the commutator at the center of the brush.

Referring to the drawings:

Figure 1 is a top view of a brush holder and commutator embodying my invention.

Fig. 2 is an end view of the brush holder and commutator.

Fig. 3 is a perspective view of the brush clamp.

Fig. 1 is a front view of the brush holder prongs.

Fig. 5 is a view of a modified form.

Fig. 6 is a perspective view of the clamp used in the modification of Fig. 5.

Fig. 7 is a modified form of brush clamp. To carry out my invention, I aflix a clamp 65 1 around the brush 2 so that the brush can- Specification of Letters Patent.

Patented Feb. 4, 1919.

Serial No. 92,152.

- not slide therethrough. In the drawing I the adjustment is made the brush will be reclamped by tightening the screw.

The clamp 1 has projections l adapted to engage projections 6 which are integral with or otherwise secured to prongs 7 on the holder arms 8.

The invention can be used with one or an number of brushes, but I have illustrated it in connection with two brushes, and in such an arrangement it is convenient to have one brush holder for the two brushes. This makes it desirable to have three of the prongs 7 on the holder and two holder arms 8, although this may be varied Without departing from the spirit of the invention.

The holder arms 8 may be secured to the brush rocker arm 9 by a rod 10 passing through holes 11 in the arms. Set screws 12 bind the brush holder in any position on the rod 10 so that it can be adjusted to the desired height above the commutator 13. The brushes are yieldingly forced against the commutator by any means, shown by way of example as springs 1 f having one end coiled around the 'shaft'lO and secured thereto by screws 15, while the other end rests on the center'point of the frame, as clearly shown in Fig. 2. In order to insure that the springs exert their forceat the center of the brush, it is preferable to bend the ends into an are as shown at 16.

As indicated in Fig. 1, there is a spring 14 bearing on top of the clamp 1 at each side of the brush. As previously stated, the springs may be of any form and they may have various means for adjusting their tension, but in the more or less diagrammatic form illustrated on the drawing, the adjustment would be made by loosening a set screw 17 in the rocker arm and turning the rod 10 until sufficient tension is obtained. On screwing down the set screw this tension will be maintained.

The operation of my improved form of brush holder will now be described. The holder arm will be adjusted toward the com mutator so that the center plane of the projections 6 is tangent to the surface of the commutator, and in order to permit this the commutator has been previously grooved at 18 sufficiently to give proper clearance. When the holder arms have been adjusted to the position referred to, they are clamped rigidly to the rod 10 by set screws 12. The brush is then placed in position with the projections 4 abutting against the projections 6 on the holder prongs, as clearly shown in Figs. 1 and 2. The ends of the springs 14 are next placed on the brush clamp to force the brush radially onto the commutator. With this position of the brush holder, the reactive force of the brush, indicated by arrow 19, is exactly in the same line as the turning force of the commutator, indicated by arrow 20. Consequently there will be no vibration, no chattering and no tilting of the brush during the operation of the motor.

In Fig. 5 a modification is shown with the projections 4 extending downward from the bottom edge of the brush clamp 1, instead of along the outside. This permits of the use of a smaller slot in the commutator and also enables the brushes to be placed closer together. There consequently will be less waste surface of the commutator.

When my improvement is to be used on dynamo electric machines that are reversible in operation, I may make two projections on the clamp 1, as shown in Fig. 7. The projection on the holder arm would therefore exert a reactive force on the brush in either direction of rotation. This is only approximately correct in principle, as the two edges 5 of the-projections are not in the central plane of the brush. However, the results obtained will be much better than with types already in use.

It is preferable to take the current off the brush by pigtails 21 which may be secured to the brush and brush holder in any well known manner.

Copies of this patent may be obtained for five cents each, by Washington, D. 0.

In case brushes are used that have a height not much greater than their thickness, one

spring only maybe used, and this may bear able conductor, means for collecting current.

from the surface of said conductor, a stationary holder engaging said means at points substantially in a plane tangential to the conductorat thecenter of the said collecting means.

2. In dynamo electric machines, a movableconductor, means for collecting current from the surface of said conductor, projections at the center of the sides of said means substantially in a plane tangential to said conductor, a stationary holder engaging said projections, and a spring exerting pressure to force said means against the conductor.

3. In dynamo electric -machines, a movable conductor, a brush, a clamp around said brush having-two members adapted to lie substantially in a plane tangential to; th e conductor at the center of the brush, a spring to force the brush against theconductor, and a brush holder engaging said members.

4. In dynamo electric machines, a cylindrical commutator, a brush adapted to contact therewith, a clamp secured to said brush and having two members projecting at the sides below the current collecting surface of said commutator, and a holder engaging said projectionssubstantially in the plane of the current collecting surface of the commutator at the center of the brush, said conductor being circumferentially grooved to provide clearance for said projections.

In testimony whereof, I hereunto affix my signature.

EMERSON L. CLARK.

addressing the commissioner of Eaten. 

